ABSTRACT

SYNCRIP, a member of the cellular heterogeneous nuclear ribonucleoprotein (hnRNP) family of RNA binding proteins, regulates various aspects of neuronal development and plasticity. Although SYNCRIP has been identified as a component of cytoplasmic RNA granules in dendrites of mammalian neurons, only little is known about the specific SYNCRIP target mRNAs that mediate its effect on neuronal morphogenesis and function. Here, we present a comprehensive characterization of the cytoplasmic SYNCRIP mRNA interactome using iCLIP in primary rat cortical neurons. We identify hundreds of bona fide SYNCRIP target mRNAs, many of which encode for proteins involved in neurogenesis, neuronal migration and neurite outgrowth. From our analysis, the stabilization of mRNAs encoding for components of the microtubule network, such as doublecortin (Dcx), emerges as a novel mechanism of SYNCRIP function in addition to the previously reported control of actin dynamics. Furthermore, we found that SYNCRIP synergizes with pro-neural miRNAs, such as miR-9. Thus, SYNCRIP appears to promote early neuronal differentiation by a two-tier mechanism involving the stabilization of pro-neural mRNAs by direct 3ʹUTR interaction and the repression of anti-neural mRNAs in a complex with neuronal miRISC. Together, our findings provide a rationale for future studies investigating the function of SYNCRIP in mammalian brain development and disease.

摘要

SYNCRIP 是 RNA 结合蛋白的细胞异质核核糖核蛋白 (hnRNP) 家族的成员，调节神经元发育和可塑性的各个方面。尽管 SYNCRIP 已被确定为哺乳动物神经元树突中细胞质 RNA 颗粒的一个组成部分，但对介导其对神经元形态发生和功能的影响的特定 SYNCRIP 靶 mRNA 知之甚少。在这里，我们使用 iCLIP 在原代大鼠皮质神经元中全面表征细胞质 SYNCRIP mRNA 相互作用组。我们识别数百个善意的SYNCRIP 靶向 mRNA，其中许多编码参与神经发生、神经元迁移和神经突生长的蛋白质。根据我们的分析，除了先前报道的肌动蛋白动力学控制之外，编码微管网络组件（例如双皮质素（Dcx））的 mRNA 的稳定性作为 SYNCRIP 功能的新机制出现。此外，我们发现 SYNCRIP 与前神经 miRNAs 有协同作用，例如 miR-9。因此，SYNCRIP 似乎通过两层机制促进早期神经元分化，包括通过直接 3'UTR 相互作用稳定前神经 mRNA 和在与神经元 miRISC 的复合物中抑制抗神经 mRNA。总之，我们的研究结果为未来研究 SYNCRIP 在哺乳动物大脑发育和疾病中的功能提供了依据。